1. Technical Field
The invention relates generally to a history state of data in data retaining device, and more particularly, to a method and system for determining a history state of data in a data retaining device based on a state of a partially depleted silicon-on-insulator (PD SOI) device coupled to the data retaining device.
2. Background Art
A history state of a piece of data in a data retaining device needs to be determined for various applications. A history state of data refers to a state of the data regarding any activities and inactivities (idling) that have been involved with the data since the data was stored in a data retaining device. For example, a multi-port cache is usually limited in size so that if the cache is full, some of the items in the cache need to be removed to make room for new items. A cache replacement algorithm is usually used to select items to be removed. Examples of cache replacement algorithms include a Least Recently Used (LRU) algorithm which discards the least recently used item first, and a Least Frequently Used (LFU) algorithm which discards the least frequently used item first. These algorithms require keeping track of a history state of the data, e.g., a history of the usage of the data.
For another instance, a history state of data may also need to be determined to monitor a validity of a particular machine state or a condition code in a processor. For example, to monitor whether a new clock cycle has been validly propagated into a latch, a history state of data retained in the latch needs to be determined.
According to the present state of the art technology, it is very expensive to determine a history state of data in a data retaining device. Based on the above, there is a need in the art for a solution to determine a history state of data in a data retaining device in an inexpensive/efficient way.